The present invention relates generally to meters for measuring utilities consumed at a residence or business and more particularly to a microprocessor-based automatic remote metering system for measuring the consumption of utilities, such as electric power, water, gas and the like.
Presently utilities, such as electric power, water, gas and the like, are sold to residential and business consumers on a usage metered basis. Generally, separate metering devices are used for each utility, with each meter requiring periodic reading by the consumer or by utility company meter readers. The vast majority of utility meters in use today are either mechanical or electromechanical devices which convert measured utility consumption into some form of rotary movement to advance a rotary dial or cylinder which provides a visual indication of utility consumption. Mechanical or electromechanical meters of this type are inherently inaccurate, particularly at low consumption levels. As an example, a conventional electrical power meter or watt hour meter typically does not respond at energy levels below 32-38 watt seconds. To the electric utility company, the energy consumption below this level represents unbilled energy. The cumulative effect of this lost billing is substantial, when totaled for a year across the entire customer base. In addition, electromechanical meters consume power in making the measurement. The power consumed by a typical watt hour meter costs each consumer an average of about $12.80 a year. Hence, both the utility company and the consumer would benefit from a more accurate and efficient meter.
Aside from inaccuracy and high power consumption, conventional utility meters do not have remote reading capabilities, nor can they be easily retrofitted to include remote reading capabilities. The remote reading capability would eliminate the time and expense of walking door-to-door to read each meter and would, therefore, be a very desirable feature.
In addition, in some applications such as in multiple dwelling apartment complexes, in office complexes, in schools and universities, in large corporations, and in companies that use heavy equipment, it is also very desirable to have remote reading capabilities. In these applications, a form of submetering would be desirable, in that it would allow the complex owner or company manager to collect and monitor utility usage from a centralized vantage point. In apartment and office complexes, the ability to effect submetering would result in a fair distribution of utility billing to the tenants. In schools, universities and large corporations, submetering would permit these organizations to conserve energy by locating where utilities are wasted. In addition, companies which use heavy equipment could use submetering to provide a peak demand alarm to alert the plant manager when the level of consumption increases into a higher billing rate level. The company could then shed some of the load it is using in order to return to a lower billing rate level. Prior art metering systems do not adequately address these considerations.
Most present day meters are designed to be manually read, say at monthly intervals, and provide a readout of the total cumulative consumption to date. Conventional meters do not provide time of use information, that is, information concerning the instantaneous consumption at a preselected time. In the electric power industry, for example, time of use information can be quite useful and important. Electric consumption is not ordinarily uniform throughout the day. In the summertime, for example, consumption is ordinarily much higher during the hot hours of the day when air conditioning equipment is running. In larger metropolitan areas, particularly those with heavy industry, the air conditioner load coincides with the business and industrial load to create a peak energy demand which may be much higher than the average demand throughout the year. To prevent brownouts or blackouts, the electric utility company must have enough ready reserve of generating equipment to supply this peak demand. During off peak hours this reserve is unused. It is naturally expensive to maintain a ready reserve to supply peak demand, particularly since the reserve periodically stands idle. It would, therefore, be desirable to bill electric consumption at a higher rate during peak hours and at a lower rate during off peak hours. In order to apply the correct billing rate, it is necessary to be able to determine not only how much power was used but also when. Time of use metering is, therefore, highly desirable.
In addition to time of use metering for peak/off peak billing purposes, time of use data would also be potentially useful in monitoring the utility needs of the customer base in planning for future expansion, in optimizing the utility network and in trouble shooting power outages and service interruptions. In the electric utility industry, for example, it is helpful to have time of use information when selecting the power rating of distribution transformers, in balancing a three-phase distribution system so that each phase is equally loaded, and in trouble shooting and locating the cause of power surges or dropouts. Present day utility meters are generally deficient in providing this information.
The present invention represents a marked improvement over prior art utility meters. The invention comprises at least one and optionally several means for sensing utility usage. Electric power consumption is measured using a magnetic field responsive device which includes a Hall effect device. The sensor is quite accurate, even at low energy consumption levels, and provides no insertion loss to affect accuracy. In addition to sensing electric power consumption, the invention is also capable of receiving, arbitrating and processing signals from other utility sensors including water flow sensors, gas flow sensors, and other utility metering devices. Further, the invention can also sense and report emergencies such as fire or intrusion.
The invention further comprises a processor or microprocessor which responds to the utility sensor or sensors and provides digital information indicative of utility usage. A memory, such as a random access memory, is coupled to the processor for storing the digital information. The processor also includes analog to digital interfacing equipment for converting analog signals of the utility sensor into digital signals for manipulation by the microprocessor. A display, such as an LED or liquid crystal 7 segment display, is responsive to the processor and provides a visual indication of the digital information provided by the processor. In addition, a communication means is coupled to the processor for transmitting the digital information to a location remote from the meter. The communication means may be adapted to communicate over a telephone system, over a fiber optic communication system or over other communication links, including transmission lines and radio links. When telephone communication is employed, the processor provides an output for serial communication with a modem circuit.
In addition to providing a visual indication of utility usage via the display and a remote indication via the communication means, the invention further comprises a control means for causing the processor to monitor the digital information as it is received or at periodic intervals and to provide an alarm event indication in response to a predetermined fault condition. For example, the processor can be programmed to respond to an interruption in utility service or a degradation in utility service by storing a record of the event and the time at which the event occurred in memory. The memory may be accessed remotely through the communication means to get details of the alarm event even after it has occurred. In the alternative, the processor can automatically provide an alarm event indication to the central office, monitoring substation or other remote location via the communication means. The electronic circuitry of the invention derives its primary operating power from the utility itself and may include a backup power source comprising a storage battery and a low battery detection circuit. Upon primary power failure, the battery backup power source operates the processor and associated circuitry to ensure that no data is lost.
The invention is housed in an enclosure which prevents physical tampering with the electronic circuitry. The entire package, including housing, is capable of being mounted into an existing four-jaw meter socket. The enclosure includes a tamper detection device associated with the housing and coupled to the processor. The tamper detection device transmits a tamper alert signal which the processor can output through the communication means to the home office or monitoring substation. To provide further protection against meter malfunction due to processor lockup, a watchdog circuit is coupled to the processor and provides a reset signal in response to processor inactivity for a predetermined length of time. If the processor becomes inactive or locks up due to tampering or spurious power line signals, the watchdog circuit detects this condition and restarts the processors control routine.
The invention is further capable of providing a utility metering system for metering multiple utility users. In accordance with the invention, a plurality of utility metering devices responsive to the utility consumption of the utility users provide utility data signals indicative of the consumption. At least one data collection computer is provided, having data input/output means for communicating with the metering devices. The data collection computer collects the utility data signals provided by the utility metering devices. A billing computer has a means for communicating with the data collection computer and for receiving the collected utility data signals from the data collection computer. In this fashion, a submetering system may be constructed in which a great number of individual utility meters can communicate with a data collection computer, which in turn can be networked with a great number of other data collection computers for communicating with a central billing computer. The individual utility metering devices may be located in each apartment of a multiple dwelling apartment complex, for example, while the data collection computer may be located in the manager's office. If desired, at least one of the utility meters may be provided with a means for sensing fire or intrusion into a protected space. Thus, the utility metering system can also alert the manager or tenant of an emergency such as fire or breaking and entering. The data collection computer can also include an automatic telephone dialer and communication device for placing a telephone call in response to the emergency condition or in response to a predetermined utility usage. In addition, the data collection computer can also be provided with both audible and silent alarms for providing an alerting signal in response to emergencies or in response to predetermined utility usage.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the accompanying drawings and to the following specification.